Effect Of Fertilizer Levels And Tillage Methods On Nitrogen And Phosphorus Loss In Double Cropping Rice Field And Red Soil Slopes Rotated With Radish And Peanut

Content:To reduce the nutrients loss of farmland due to eutrophication, the test including two parts, one part is designning 4 treatments:fallow-rice-rice (without fertilization), green manure-rice-rice (early rice with single-green manure and later rice without fertilization), green manure-rice-rice (early rice with green manure and chemical fertilizers, late rice without fertilization), fallow-rice-rice (conventional chemical fertilizers) to researching on the influence of surface water nutrient concentrations and soil nutrients in different layer and yield when making use of winter fallow paddy field planting green manure as organic fertilizer sources,another part is designning 5 treatments: no fertilization+down slope tillage (CK), normal fertilization+down slope tillage (CA), optimized fertilization+down slope tillage (OA), optimized fertilization+cross slope ridge (OH), optimized fertilization+cross slope ridge+straw mulch (OHB) to researching on the influence of nutrient utilization and runoff on the dry land by different fertilization amount and different farming measures.The results are as follows:1. Nitrogen and phosphorus concentration in surface water of paddy field is closely related to runoff loss of nutrients and this test research on dynamic change of nutrient concentrations in paddy field with different types of fertilizers.The results showed that:the highest concentration value of TN,NH4+-N in the third treatment and the fourth treatment are both appeared in the first day after fertilization,the maximum TN concentration after three times fertilization are 84.60 mg/1,26.87 mg/1,56.0 mg/1 and the fourth treatment are 116.78 mg/1,40.0 mg/1,62.7 mg/1 and rapid decline later, TN concentration decreased to 2.2 mg/1,3.63 mg/1 and 5.34 mg/1 of the third treatment and 1.40 mg/l,4.27 mg/l,8.13 mg/l of the fourth treatment in the ninth day after fertilization.Therefore,within 10 days after fertilizer is the critical period of control runoff loss. The highest value of the concentrations of TP and STP appeared in the first day after base fertilizer of the third treatment and the fourth treatment, TP and STP concentrations were 2.58 mg/l,1.76 mg/l of the third treatment and 2.89 mg/l,2.16 mg/l of the fourth treatment, and were significantly difference. Such as nitrogen rapid decline later.The surface water nutrient concentrations are closely related to fertilizer amount; the nitrogen loss form is IN and NH4(?)-N in paddy field surface water.2. Tests are research on nutrients variation in different soil layer on paddy field when applying different kinds of fertilizer, the results showed that:at milk vetch seedling and flowering stage, the total nitrogen content in different soil treatments has no significant difference;at the early rice harvest stage, the total nitrogen content of single milk vetch-applying treatment (except 0-20cm) are always significantly higher than the chemical fertilizer treatment;the NH4+-N content changing trend of different treatments in different soil layer are similar to total nitrogen; at milk vetch seedling and flowering stage,NO3--N content changing trend of different treatments in different soil layer have significantly difference,NO3--N content of fertilizer treatment is the highest,secondly,the milk vetch treatment,control treatment was the lowest;at milk vetch seedlings stage,available phosphorus content of single milk vetch-applying treatment was higher than the chemical fertilizer treatment in different layers;in the milk vetch flowering available phosphorus content is opposite to the former;at early rice harvest, available phosphorus content of single milk vetch-applying treatment in 0～20 cm and 20～40 cm soil layer are higher than the chemical fertilizer treatment,and the remaining layers are the opposite.3. Tests are research on the influences about nutrients absorbing amount and yield when applying different kinds of fertilizer,results showed that:applying the equivalent amount nitrogen fertilizer, nitrogen absorbing amount of the third treatment and the fourth treatment have no significant difference, nitrogen absorbing amount of early rice straw and paddy in the third treatment are 20 kg/hm2 and 49 kg/hm2, in the fourth treatment are 17 kg/hm2 and 50 kg/hm2; early rice straw and paddy phosphorus absorbing amount of single milk vetch-applying treatment are 1 kg/hm2 and 5 kg/hm2, that are equivalent to the control treatment which are 1 kg/hm2 and 3kg/hm2,applying the equivalent amount phosphorus fertilizer, phosphorus absorbing amount of the third treatment and the fourth treatment have no significant difference, phosphorus absorbing amount of early rice straw and paddy in the third treatment are 3 kg/hm2 and 11 kg/hm2, in the fourth treatment are 2 kg/hm2 and 11 kg/hm2. Applying the equivalent amount fertilizer, the yield of early rice straw and paddy in the third treatment and the fourth treatment have no significant difference, the straw yield are 2880 kg/hm2和2872 kg/hm2, the paddy yield are 5473 kg/hm2和5813 kg/hm2. The later rice nitrogen absorbing amount of straw and paddy in the first treatment, the second treatment the third treatment have no significant difference, nitrogen absorbing amount of straw are 11～12 kg/hm2 and paddy are 32～36 kg/hm2; the phosphorus absorbing amount of later rice condition is ditferent to the nitrogen absorbing amount,straw and paddy in the third treatment and the fourth treatment are 5 kg/hm2和14 kg/hm2,which has a little higher than the first treatment which is 2 kg/hm2 and the second treatment which is 8～9 kg/hm2.The yield of applying fertilizer treatment has the common amount,which the straw amount is 2350 kg/hm2 and the paddy is 5208 kg/hm2.4. Test of different fertilizer levels and different tillage practices on sloping land of red soil and crop nutrient utilization of surface runoff, the results show that:nutrient absorption of radish and peanut are not be reduced, and radish nitrogen utilization rate improve 15% and peanut improve 3.3%,when the amount of nitrogen fertilizer be poperly reduced, meanwhile, potassium increased for radish and phosphorus increased for peanut, but phosphorus utilization rate very lower and have no changes (radish is 8.55%～8.73% and peanut is 2.47%～2.63%); The runoff volume positively correlated with rainfall amount significantly during the same period and the quotiety is to 0.86;Take the methods of ridge culture reduce runoff 0.43×105 L·hm-2,straw mulching and also ridge culture reduce runoff 0.14×105 L/hm-2 than only ridge culture;Difference of total nitrogen and total phosphorus concentration among different treatments in the runoff water are not significant, but soluble nutrient (NH4+-N, NO3--N and STP) have differences in later stage, there are great changes at different growing stages, that is mainly related to fertilizer and farming activities and rainfall nutrient concentration; Nutrient total loss amount were proportional to fertilization amount;Nitrogen loss mainly as the form of sediment combined,NO3--N is the mainly form of dissolved inorganic nitrogen that account for 10.53～12.48% of TN, secondly, NH4+-N that account for 6.19%～8.33% of TN,phosphorus loss also mainly as the form of sediment combined and STP counted for 29.38%～40.74% of TP.